Simultaneous reduction of NO and KCl during injection of ammonium sulphate in a biomass fired BFB boiler

Paper in proceeding, 2017

Sulphate containing additives, such as ammonium sulphate (AS), are used for sulphation of KCl during biomass combustion. Another aspect with injection of AS is that a significant NOx reduction is achieved but it may also have an impact on other flue gas components. Operating parameters such as the air excess ratio and the presence of combustibles could also have an effect on the flue gas chemistry involving NO and KCl. This paper is based on results obtained from a measurement campaign during combustion of demolition wood in a 63 MWth Bubbling Fluidised Bed (BFB) boiler. Ammonium sulphate was injected for simultaneous reduction of NO and KCl at two positions in the boiler i.e. in the upper part of the combustion chamber and in the empty pass. The impact of AS on the flue gas chemistry was investigated at different operating conditions. Several measurement tools including, IACM (online measurements of gaseous alkali chlorides) and gas analysis were applied. The position for injection of AS as well as the operating parameters had an impact on the flue gas chemistry for reduction of both NO and KCl.